Wednesday, October 31, 2012

[Herpetology • 2012] Kihansi Spray Toad | Nectophrynoides asperginis • Reintroduction in Udzungwa Mountains, south-central Tanzania

‘Extinct’ Toad Returns Home

Kihansi Spray Toad, Nectophrynoides asperginis, is a dwarf toad, which rarely grows to be more than 2cm long.

The Kihansi Spray Toad, Nectophrynoides asperginis, was restricted to the smallest known range for any vertebrate species, with an estimated historic wild population of 17,000 toads found within 2 hectares of waterfall spray zone in the Kihansi Gorge of the Udzungwa Mountains in south-central Tanzania. Only discovered by scientists in 1996, the thumbnail-sized golden colored toad was believed to be extirpated from its small patch of habitat in 2004, and was officially declared Extinct in the Wild by the International Union for Conservation of Nature (IUCN) in October 2009.

In reference to the specialized biology of the Kihansi Spray Toad, University of Dar es Salaam professors, Dr. Charles Msuya and Dr. Kim Howell, one of the scientists to discover the toad in 1996, jointly wrote, “The Kihansi Spray Toad is unique because of its specialized habitat. It was endemic to Tanzania, in the ‘spray meadows’ at the base of the Kihansi Falls that received more than 70 mm of ‘rain’ per day in the form of spray from the falls prior to the construction of the Lower Kihansi Hydropower Project dam. Very few species of amphibians can survive in this habitat. The KST is also unusual because its life cycle does not have a free swimming tadpole stage, but rather, females give birth to tiny froglets.”

The species’ rapid decline followed hydroelectric dam construction upstream from its habitat that resulted in a nearly complete loss of the “spray meadow” habitat that the species depended on, and coincided with the emergence of the amphibian chytrid fungus, a disease that has been implicated in amphibian extinctions in several parts of the world. In November 2000, at the invitation of the Tanzanian Government, 499 toads were collected and transferred to the Wildlife Conservation Society’s Bronx Zoo, and later the Toledo Zoo, to initiate a captive breeding program which is now represented by over 6,000 toads. In 2010, a captive colony was established in Tanzania by University of Dar Salaam and National Environmental Management Council researchers who had facilities constructed specifically for the conservation of the small toad in Dar es Salaam and at the base of the Kihansi Gorge.

“The level of collaboration from the Tanzanian government and the participating zoos, to the Tanzanian field biologists and students who shared their knowledge with us, has been nothing short of inspiring. This is one of the great stories of amphibian conservation,” said R. Andrew Odum, curator of herpetology at the Toledo Zoo. “The Bronx Zoo has been working with our partners, including the Toledo Zoo, for more than a decade to save this species and reintroduce it back into the wild. This landmark occasion is reason to celebrate,” said Jim Breheny, Executive Vice President and General Director of WCS Zoos & Aquarium and Director of the Bronx Zoo.

In 2010, the Lower Kihansi Environmental Management Project (LKEMP) within Tanzania’s National Environmental Management Council (NEMC) and the University of Dar Salaam organized Tanzanian researchers and an international team of conservation biologists and pathologists from the Toledo Zoo, the Wildlife Conservation Society, the IUCN SSC Amphibian Specialist Group, the IUCN SSC Re-introduction Specialist Group, Global Wildlife Conservation, and other partners to develop a plan for reintroducing the Kihansi Spray Toad to its native habitat. The reintroduction plan set a timeframe to address causes of the KST decline as well as carry out a series of experiments to ensure the species’ survival in the wild. At this stage, preliminary ‘soft’ release studies involving toads within mesh cages situated in the native habitat have shown success.

Prior to its reintroduction, several initiatives were made to restore the Kihansi Gorge ecosystem. These included the installation of an expansive misting system designed to replicate the spray zone habitat that was lost after dam construction, and building of bridges and walkways to facilitate monitoring of the gorge. Funded by the World Bank and the Government of Norway, the misting system has been running since late 2000 in order to restore and maintain the native vegetation that the toads once lived amongst, and the invertebrates upon which they fed.

Today, October 30th, 2012, the missing amphibian that has been the focus of much attention in Tanzania and around the world was returned to its niche within this unique ecosystem. The initial release represents a total of 2,500 animals flown to Tanzania from the Toledo and Bronx Zoos in June and earlier this month. The animals made their international journey safely and were acclimatized before their release. Future releases are expected as researchers work towards reestablishing a viable population in the wild. The reintroduction of the Kihansi Spray Toad is being led by researchers from the University of Dar es Salaam, the National Environment Management Council of Tanzania, and Tanzania Wildlife Research Institute, in international collaboration with scientists from the University of Georgia’s Savannah River Ecology Laboratory, Toledo Zoo, Wildlife Conservation Society, IUCN SSC Amphibian Specialist Group, and Global Wildlife Conservation.

“Most reintroductions for amphibians and reptiles have been designed to establish or augment a population of a rare species, but it is extremely exciting to be involved in actually returning a species that was extinct in the wild back to its native habitat.” said Dr. Kurt Buhlmann and Dr. Tracey Tuberville, research scientists with the University of Georgia’s Savannah River Ecology Laboratory and Associate Conservation Scientists with Global Wildlife Conservation. Drs. Tuberville and Buhlmann went on to say, “This project is a shining example of international collaboration, linking tremendous effort by the Tanzanians to recreate the unique habitat, with successful captive breeding programs, and a scientific approach to implementing the reintroduction for a species that was nearly lost.”

A third of the world’s approximately 7,000 amphibian species are threatened with extinction. Hundreds of species are thought to have gone extinct within the past few decades due to habitat loss, disease, and other factors. The reintroduction of the Kihansi Spray Toad represents a tremendous success story in amphibian conservation thanks to swift action by the Tanzanian government and an international effort by collaborating organizations. It is one of only a handful of amphibian species, globally, to have been saved from extinction through an intensive captive breeding program. Now that it has returned to its restored habitat, the Kihansi Spray Toad represents the world’s first reintroduction of an ‘Extinct in the Wild’ amphibian.

“As a signatory to the Convention on Biological Diversity (CBD) and Convention on International Trade on Endangered Species (CITES), key decisions were taken followed by initiatives to restore the Kihansi Gorge ecosystem. Reintroduction of Kihansi Spray Toads and other ongoing efforts depict Tanzania’s commitment towards the conservation of biodiversity as well as balancing water needs among the different users.” said Mr. Sazi Salula, the Permanent Secretary of Tanzania at the Vice President’s Office.

Co-Chair of the IUCN SSC Amphibian Specialist Group, Dr. Claude Gascon, stated, “The success story of the small Kihansi Spray Toad can teach us big lessons for the future of biodiversity conservation. While amphibians and other species are incurring severe threats to their survival, it is never too late to use the best science and conservation action to save a species and its habitat. This success story has only been possible with the help and partnership of many organizations around the world and the leadership of the Government of Tanzania, and the belief that no species and no situation is too dire to try to save life on Earth. Extinction in the wild is not forever.”